How do i begin with it?

I really struggle with either forming ideas or if i have an idea i automatically start to notice the complexities in it or that something similar to my idea is already existing in the market. I really wanna work on something in the mental wellbeing field related to technology but all the recent fast developments have made me doubt my ideas alot, what if a tech giant is planning or will plan something like that in the future? I dont wanna follow this quick money thing but rather build something impactful and useful for people, But i have No past experience in this as i am fairly young (17) and dont know where shall i start with, Any advice on how i should start with will be incredibly helpful